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This article presents the historical background, the principle and case studies of electrodialytic remediation of heavy metal polluted soil. Remediation of fine grained soils polluted by heavy metals is problematic for most traditional methods such as pump and treat technologies and soil washing methods. On the other hand, electrochemical soil remediation methods are particularly suited for the fine grained soils. These methods are based on an applied electric current as cleaning agent. The current tends to pass the soil through the finest pores, i.e. next for the smallest soil particles, where the heavy metals are mainly adsorbed.

The heavy metals are mobile in the electric field as ions in solution, only. This means that the heavy metals must be desorbed during the process. For some soils it is necessary to add an enhancement solution to aid this desorption, whereas for other soils addition of water is sufficient to the remediation to occur.

Electrodialytic soil remediation was applied at laboratory scale for different soil and pollution combination. Soils with a low carbonate content and polluted with Cu, Pb and Zn are shown remediated by the electrodialytic method without use of enhancement solution to improve the mobility of the metal ions. It was shown possible to remove 97% Cu in one experiment and 87% Pb and 69% Zn in another experiment. During the electrodialytic process the soil becomes acidified, thus desorbing these metal ions. Further a carbonate soil polluted by Cu can be remediated using ammonia as enhancement solution. Indeed, Cu forms mobile complexes with ammonia. Thus the soil can be remediated at high pH, at which the carbonates are not dissolved. It was shown that addition of ammonia improved the remediation from nothing removed from the soil totally without ammonia to 73% Cu removed after addition of ammonia. In the case of wood preservation sites where the soil is polluted by Cu and As, ammonia can also be used as enhancement solution, since As is mobile in the alkaline environment. In an experiment 70% As and 53% Cu was removed. Nonetheless, for wood preservation sites polluted with Cu, Cr and As ammonia is not sufficient. Here ammonium citrate showed potential, since the citrate part is mobilizing Cr. Experimentally 33% Cr, 65% Cu and 66% As was removed from the soil at the same time after addition of ammonia citrate. Thus, by carefully choosing the enhancement solution for each case, electrodialytic remediation is possible, even of soils with a fine fraction ranging from 33% to 63% per weight as the experimental soils here.

The service life of wood treated with Chromated Copper Arsenate (CCA) may be 30 years or even more due to the strong fixation of CCA in wood. The strong fixation also means that when the wood is removed from service, a large proportion of the copper, chromium and arsenic is still present and will enter into the waste stream unless actions are taken to prevent this. While the use of CCA is regulated in many countries, the handling of the waste wood is often not. The amount of treated wood being removed from service is expected to increase dramatically over the next few decades.

A method for safe handling of the waste wood and reuse of the wood resources, the contains — energy and metals, — would be environmentally beneficial. Here we tested electrodialytic remediation as a remediation method. Preliminary results show that more than 90% copper and approximately 85% chromium and arsenic are removed from the wood.

When the method will be optimised, it is expected that close to 100% of the metals will be removed during remediation. Afterwards the metals can be recovered and possibly reused in new wood preservatives. The wood chips can be reused or burned as it no longer contains metals.

The present study has been undertaken to investigate a process that might remove inorganic mercury from mine waste water streams by using a compound of the crandallite type. In this work, an artificial amorphous crandallite, Ca Sr Al(OH)(HPO)(PO), was synthesized in our laboratory and studied for the separation, removal and recovery of mercury from mercurial wastewaters. Since this compound exhibits an extremely wide range of ionic substitutions, Ca and Sr were interchanged with mercury. As a result, the mercury content of the waste water, ranging initially from 70 to 90 mg l, was reduced to less than 0.1 mg l. The process has been studied under batch conditions. The crandallite has been shown to have a high capacity for the absorption of mercury from mercuric nitrate solutions. The exchange capacity values of crandallite range from 0.90–1.50 meq g. The equilibrium and kinetic behaviour was also studied.

In this work the ability of some vegetable wastes from industrial processes such as cork and yohimbe bark, grape stalks and olive pits, to remove metal ions from aqueous solutions has been investigated. The influence of pH, sodium chloride and metal concentration on Ni(II) and Cu(II) uptake was studied. Metal uptake showed in all the cases a pH-dependent profile. Maximum sorption was found at an initial pH around 5.0–6.0. In some cases an increase of sodium chloride concentration induced a decrease in metal removal. Adsorption isotherms at the optimum pH were expressed by the noncompetitive Langmuir adsorption model. When comparing the four materials, yohimbe bark waste was found to be the most efficient adsorbent for both metals studied.

The adsorption behavior of heavy metals on arabica and robusta roasted coffee beans was investigated. To adsorb heavy metals, the coffee beans residues were suspended in aqueous solutions containing Cu(II) or Cd(II). Then the amount of heavy metal remaining in the solution was measured by atomic absorption spectrometry. The results show that the adsorption percentage of the heavy metal ions were above 90% for all coffee beans examined. Further, the adsorption capacities of Cu(II) and Cd(II) ions onto blend coffee were about 2.0 mg g. This adsorption capacity is similar to that of zeolite, activated carbon and chitosan; and is higher than that of chitin and cerite. Blend coffee was thus found to be a good adsorbent for the removal of heavy metals from wastewater.

Textile dyeing effluents containing recalcitrant dyes are polluting waters due to their color and by the formation of toxic or carcinogenic intermediates such as aromatic amines from azo dyes. Since conventional treatment systems based on chemical or physical methods are quite expensive and consume high amounts of chemicals and energy, alternative biotechnologies for this purpose have recently been studied. A number of anaerobic and aerobic processes have been developed at laboratory scale to treat dyestuff. Some industrial pilot scale plants have even been set up. Additionally, biosorption shows very promising results for decolorizing textile effluents. In this contribution, we review fundamental and applied aspects of biological treatment of textile dyes.

An anaerobic mixed population was found to be able to grow on acetate and Indigo carmine as sole carbon sources. After eighteen days of incubation, the dye was completely decolorized. Degradation products of indigo carmine monitored by high performance liquid chromatography coupled to ultraviolet/visible detector (HPLC-UV/VIS) were not detected after 25 d of incubation. Investigations on the degradation pathway of the anaerobic mixed population have been studied. To our best knowledge, it is the first time that an anaerobic mixed population growing on acetate, a dye bath additive in the textile industry, is able to mineralize indigo carmine.

The biodegradation of benzothiazole, 2-hydroxybenzothiazole and 2-aminobenzothiazole by two strains of was monitored by high performance liquid chromatography (HPLC) and by in-situ H Nuclear Magnetic Resonance (NMR), which is directly performed on culture media, without prior purification. A common biodegradative pathway is evidenced; the benzothiazole compounds were biotransformed into hydroxylated derivatives. The chemical structure of these metabolites was determined by a long range H-N heteronuclear shift correlation without any previous N enrichment of the starting xenobiotic.

The biotransformation of nonylphenol was investigated in an agricultural soil treated with a mixture of C-labelled and unlabelled surfactant. It was then studied in soil samples amended with sludges spiked with the mixture of chemicals. Nonylphenol amount in all samples of soil and soil/sludge mixtures was 40 mg kg. In the soil free of sludge, the half-life of nonylphenol was found to be 4 d. When the soil was amended with sludge from the city of Ambares, France, it was about 16 d. In the soil amended with sludge from Plaisir, a 8-day lag phase was observed before the transformation starts, and nonylphenol half-life exceeded 16 d. In each case, nonylphenol transformation resulted in mineralization as well as stabilization of the chemical as bound residues within the soil. Further, some strains of filamentous fungi were isolated from the soil/sludge mixtures and identified to belong to the and species. Most of them were able to efficiently transform nonylphenol in liquid cultures. In addition, the ligninolytic basidiomycete was able to catalyze partly the conversion of nonylphenol into carbon dioxide. Laccases purified from cultures are enzymes involved in nonylphenol oxidative coupling leading to oligomerization.

The objective of this study was to evaluate the effectiveness of in-situ trichloroethene (TCE) bioremediation, and to determine whether the observed decrease in TCE concentrations was attributable to biological degradation versus abiotic processes. An enhanced in-situ TCE bioremediation project in which groundwater amended with microbe stimulating compounds was injected into the contaminated subsurface was analyzed. Dilution, attributed to mixing between the injected clean and contaminated waters, was calculated using a modified groundwater mixing equation and chloride concentrations of the waters at various times in the study. Over the course of the trial, spatially averaged TCE concentrations within the aquifer decreased by 41%. The chloride calculations suggested that a 29% reduction may be attributable to dilution, and that only a 12% decrease in concentrations may be attributable to biological degradation.